Sandvine notes that there was a slight uptick in IPv6 traffic on June 6, just as Comcast witnessed, but points out that the big spike occurred in late May, when Netflix and Facebook enabled their sites. YouTube's had IPv6 enabled for much longer, so it's been the driving force in the category for a while:

Sandvine also noticed that it appears as though Netflix may have created its own IPv6-specific domain, rather than operating a single domain with IPv6 and IPv4 records, meaning (tsk, tsk...) Netflix "might not be in full compliance with the spirit" of World IPv6 Launch Day.

But we won't hammer them too hard. At least Netflix is on the board, while IPv6 is hardly on the radar for most of the Web. That may change, though, as Vint Cerf and the gang try to nag everyone else to get with the program posthaste. (See IPv6 Hoopla Not Over Yet.)